'\" t
.TH LESSKEY 1 "Version 590: 03 Jun 2021"
.SH NAME
lesskey \- specify key bindings for less
.SH "SYNOPSIS (deprecated)"
.B "lesskey [\-o output] [\-\-] [input]"
.br
.B "lesskey [\-\-output=output] [\-\-] [input]"
.br
.B "lesskey \-V"
.br
.B "lesskey \-\-version"
.SH SCOPE
This document describes the format of the 
.I lesskey
source file, which is used by
.I less
version 582 and later.
In previous versions of 
.IR less ,
a separate program called
.I lesskey
was used to compile the 
.I lesskey 
source file into a format understood by
.IR less .
This compilation step is no longer required and the
.I lesskey
program is therefore deprecated although the file format remains supported by
.I less
itself.
.PP
.SH FILE FORMAT
The input file consists of one or more
.I sections.
Each section starts with a line that identifies the type of section.
Possible sections are:
.IP #command
Defines new command keys.
.IP #line-edit
Defines new line-editing keys.
.IP #env
Defines environment variables.
.PP
Blank lines and lines which start with a pound sign (#) are ignored,
except for the special section header lines.
.
.SH "COMMAND SECTION"
The command section begins with the line
.sp
#command
.sp
If the command section is the first section in the file,
this line may be omitted.
The command section consists of lines of the form:
.sp
	\fIstring\fP <whitespace> \fIaction\fP [extra-string] <newline>
.sp
Whitespace is any sequence of one or more spaces and/or tabs.
The \fIstring\fP is the command key(s) which invoke the action.
The \fIstring\fP may be a single command key, or a sequence of up to 15 keys.
The \fIaction\fP is the name of the less action, from the list below.
The characters in the \fIstring\fP may appear literally, or be
prefixed by a caret to indicate a control key.
A backslash followed by one to three octal digits may be used to
specify a character by its octal value.
A backslash followed by certain characters specifies input
characters as follows:
.IP \eb
BACKSPACE
.IP \ee
ESCAPE
.IP \en
NEWLINE
.IP \er
RETURN
.IP \et
TAB
.IP \eku
UP ARROW
.IP \ekd
DOWN ARROW
.IP \ekr
RIGHT ARROW
.IP \ekl
LEFT ARROW
.IP \ekU
PAGE UP
.IP \ekD
PAGE DOWN
.IP \ekh
HOME
.IP \eke
END
.IP \ekx
DELETE
.PP
A backslash followed by any other character indicates that character is
to be taken literally.
Characters which must be preceded by backslash include
caret, space, tab and the backslash itself.
.PP
An action may be followed by an "extra" string.
When such a command is entered while running
.IR less ,
the action is performed, and then the extra
string is parsed, just as if it were typed in to
.IR less .
This feature can be used in certain cases to extend
the functionality of a command.
For example, see the "{" and ":t" commands in the example below.
The extra string has a special meaning for the "quit" action:
when
.I less
quits, the first character of the extra string is used as its exit status.
.
.SH EXAMPLE
The following input file describes the set of
default command keys used by less:
.sp
.RS 5m
.TS
l l.
#command
\er	forw-line
\en	forw-line
e	forw-line
j	forw-line
\ekd	forw-line
^E	forw-line
^N	forw-line
k	back-line
y	back-line
^Y	back-line
^K	back-line
^P	back-line
J	forw-line-force
K	back-line-force
Y	back-line-force
d	forw-scroll
^D	forw-scroll
u	back-scroll
^U	back-scroll
\e40	forw-screen
f	forw-screen
^F	forw-screen
^V	forw-screen
\ekD	forw-screen
b	back-screen
^B	back-screen
\eev	back-screen
\ekU	back-screen
z	forw-window
w	back-window
\ee\e40	forw-screen-force
F	forw-forever
\eeF	forw-until-hilite
R	repaint-flush
r	repaint
^R	repaint
^L	repaint
\eeu	undo-hilite
\eeU	clear-search
g	goto-line
\ekh	goto-line
<	goto-line
\ee<	goto-line
p	percent
%	percent
\ee[	left-scroll
\ee]	right-scroll
\ee(	left-scroll
\ee)	right-scroll
\ekl	left-scroll
\ekr	right-scroll
\ee{	no-scroll
\ee}	end-scroll
{	forw-bracket {}
}	back-bracket {}
(	forw-bracket ()
)	back-bracket ()
[	forw-bracket []
]	back-bracket []
\ee^F	forw-bracket
\ee^B	back-bracket
G	goto-end
\ee>	goto-end
>	goto-end
\eke	goto-end
\eeG	goto-end-buffered
\&=	status
^G	status
:f	status
/	forw-search
?	back-search
\ee/	forw-search *
\ee?	back-search *
n	repeat-search
\een	repeat-search-all
N	reverse-search
\eeN	reverse-search-all
&	filter
m	set-mark
M	set-mark-bottom
\eem	clear-mark
'	goto-mark
^X^X	goto-mark
E	examine
:e	examine
^X^V	examine
:n	next-file
:p	prev-file
t	next-tag
T	prev-tag
:x	index-file
:d	remove-file
-	toggle-option
:t	toggle-option t
s	toggle-option o
\&_	display-option
|	pipe
v	visual
!	shell
+	firstcmd
H	help
h	help
V	version
0	digit
1	digit
2	digit
3	digit
4	digit
5	digit
6	digit
7	digit
8	digit
9	digit
q	quit
Q	quit
:q	quit
:Q	quit
ZZ	quit
.TE
.RE
.sp
.SH PRECEDENCE
Commands specified by
.I lesskey
take precedence over the default commands.
A default command key may be disabled by including it in the
input file with the action "invalid".
Alternatively, a key may be defined
to do nothing by using the action "noaction".
"noaction" is similar to "invalid", but
.I less
will give an error beep for an "invalid" command,
but not for a "noaction" command.
In addition, ALL default commands may be disabled by
adding this control line to the input file:
.sp
#stop
.sp
This will cause all default commands to be ignored.
The #stop line should be the last line in that section of the file.
.PP
Be aware that #stop can be dangerous.
Since all default commands are disabled,
you must provide sufficient commands before the #stop line
to enable all necessary actions.
For example, failure to provide a "quit" command can lead to frustration.
.
.SH "LINE EDITING SECTION"
The line-editing section begins with the line:
.sp
#line-edit
.sp
This section specifies new key bindings for the line editing commands,
in a manner similar to the way key bindings for
ordinary commands are specified in the #command section.
The line-editing section consists of a list of keys and actions,
one per line as in the example below.
.
.SH EXAMPLE
The following input file describes the set of
default line-editing keys used by less:
.sp
.RS 5m
.TS
l l.
#line-edit
\et	forw-complete
\e17	back-complete
\ee\et	back-complete
^L	expand
^V	literal
^A	literal
\eel	right
\ekr	right
\eeh	left
\ekl	left
\eeb	word-left
\ee\ekl	word-left
\eew	word-right
\ee\ekr	word-right
\eei	insert
\eex	delete
\ekx	delete
\eeX	word-delete
\eekx	word-delete
\ee\eb	word-backspace
\ee0	home
\ekh	home
\ee$	end
\eke	end
\eek	up
\eku	up
\eej	down
^G	abort
.TE
.RE
.sp
.
.SH "LESS ENVIRONMENT VARIABLES"
The environment variable section begins with the line
.sp
#env
.sp
Following this line is a list of environment variable assignments.
Each line consists of an environment variable name, an equals sign (=)
and the value to be assigned to the environment variable.
White space before and after the equals sign is ignored.
Variables assigned in this way are visible only to
.IR less .
If a variable is specified in the system environment and also in a
lesskey file, the value in the lesskey file takes precedence.
Although the lesskey file can be used to override variables set in the
environment, the main purpose of assigning variables in the lesskey file
is simply to have all
.I less
configuration information stored in one file.
.
.SH EXAMPLE
The following input file sets the \-i option whenever
.I less
is run, and specifies the character set to be "latin1":
.sp
.nf
	#env
	LESS = \-i
	LESSCHARSET = latin1
.fi
.sp
.
.SH "SEE ALSO"
.BR less (1)
.
.SH WARNINGS
On MS-DOS and OS/2 systems, certain keys send a sequence of characters
which start with a NUL character (0).
This NUL character should be represented as \e340 in a lesskey file.
.
.SH COPYRIGHT
Copyright (C) 1984-2021  Mark Nudelman
.PP
less is part of the GNU project and is free software.
You can redistribute it and/or modify it
under the terms of either
(1) the GNU General Public License as published by
the Free Software Foundation; or (2) the Less License.
See the file README in the less distribution for more details
regarding redistribution.
You should have received a copy of the GNU General Public License
along with the source for less; see the file COPYING.
If not, write to the Free Software Foundation, 59 Temple Place,
Suite 330, Boston, MA  02111-1307, USA.
You should also have received a copy of the Less License;
see the file LICENSE.
.PP
less is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
or FITNESS FOR A PARTICULAR PURPOSE.
See the GNU General Public License for more details.
.
.SH AUTHOR
.
Mark Nudelman
.br
Report bugs at https://github.com/gwsw/less/issues.
